The pollution monitoring satellite Copernicus Sentinel-5 Precursor has been successfully launched from the Plesetsk Cosmodrome in Russia on 29th September 2017. The TROPOspheric Monitoring Instrument (TROPOMI) is the satellite instrument on board of the Sentinel-5 Precursor satellite. TROPOMI instrument maps a multitude of trace gases such as nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane, carbon monoxide and aerosols – all of which affect the air quality and therefore our health and our climate.

TROPOMI is a pushbroom spectrometer with spectral bands in the UV, VIS, NIR and SWIR. HORIBA Scientific designed, produced and characterized for the UV channel, in collaboration with TNO, a set of blazed holographic plane reflexion replica gratings based on Jobin Yvon Technology. A high groove density (2400gr/mm) holographic master grating blazed at 250nm was selected for its high efficiency and low stray light performances. This grating was characterized in efficiency on the TROPOMI UV channel range (270 - 330nm) for both TE and TM polarization (Fig. 1).The produced Qualification Model (QM), Flight Model and Spare (FM, FS) replica gratings retain the performances of the initial master holographic grating with a cost effective approach :

The QM grating has been used for performing successfully environmental tests (temperature cycling from -50°C to +45°C and humidity test at 35°C and 95% RH) according to the TROPOMI space-flight mission requirements (Fig. 3).

Fig. 3. Humidity tests performed during 24 hours on the QM grating with 35°C and 95% RH.

The TROPOMI Sentinel-5 Precursor project allowed HORIBA Scientific to participate to the European Copernicus programme and be selected as grating supplier for Sentinel-3CD and Sentinel-5.